Infrastructural interdependency

As the latest round of global weirding in the Northeast has shown us, with over 3m folks out of power – our electrical system is very fragile.  Power outages have worse outcomes than just siting in the dark. Almost every network and utility that our modern lifestyle relies on is interdependent. In a long blackout (beyond the 24 to 48 hours that most mission critical infrastructure has fuel to power their back-up generators), these other systems are bound to fail. Lots of architects and other folks have been discussing the utopian ideal of living off the grid, but our cities are the grid and thus, they can’t be unplugged quite as easily as a house. So what are the risks of power outages?

Dr. James Tindall covers the modes of interdependence and failure types:

Network Interdependency – 5 Categories

  1. Co-location – networks that are located in the same geographic area.  Cyberspace is a good analogy where servers from one company that serve a variety of companies are stored at a location with other servers owned by a larger company.
  2. Exclusive – networks that can support only one or a few outputs (these can be transient in nature) such as water distribution networks or oil/natural gas pipelines.
  3. Input – products or outputs from one network that is used by another.
  4. Mutual – networks that serve as inputs for another such as water and power generation (Hoover Dam) or oil and power generation.
  5. Shared – networks that share facilities, physical components or transport mechanisms.

Types of Network Failure

    1. Common Cause – a failure due to a single attack that will immediately or directly impact two or more networks or infrastructures, which would typically be of the co-location interdependency.
    2. Cascade – failures that quickly spread from one network or infrastructure to another such as the input or mutual types described above.
    3. Escalating – where the failure in one network or infrastructure exacerbates failure in another such as the exclusive or shared types.  As an example, a failure in transportation could cause delays or failures in emergency response, telecommunications or electrical repair.

The risks of failure are much higher than most engineers and policy makers like to acknowledge (re: Fukashima) as system complexity increases. So we all need to get ready for the lights to go out and to stay out for a long time in our lifetime.

Centerpoint Energy has a cute cartoon of common power outage causes (which mostly sidesteps the electrical utilities culpability):

To really get your geek out on infrastructural interdependency and blackout risks, check out:

The US electrical grid:

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